When Larry Smith came across the scruffy, bearded nomad on the Appalachian Trail last month, he dubbed him the "fight angel."

James Jordan seemed to appear out of nowhere. While "trail angels" provide water and food to weary hikers along their journey, Smith said Jordan was combative, threatening people and trashing shelters. Tales of his aggressive demeanor preceded him as he roamed a nearly 150-mile span of the rugged trail during peak season.

Smith said Jordan poured alcohol on a campfire where hikers were gathered at the Partnership shelter in Marion, Virginia, flaring the flames.

"He told us he was going to burn the shelter down," said Smith, a Charleston, South Carolina, baker. "He was looking for something. He wanted a fight."

Smith called police, but by the time officers arrived that April 1 night, the man had disappeared into the darkness. The weeks that followed brought more disturbing encounters with people walking the trail in Virginia, North Carolina and Tennessee, and with law enforcement.

Then, on Saturday, May 11, authorities said, Jordan, armed with a large knife, attacked a group of hikers on the trail in Virginia. A man was killed and a woman critically injured in the twilight-hour assault that sent other hikers running for safety.

The attack, which occurred not far from where Smith saw Jordan, has deeply jolted the close-knit hiking community. People along the trail, which stretches 2,100 miles from Georgia to Maine, look out for one another and pride themselves on being welcoming. They use an app to communicate potential dangers such as bear sightings, and violence of this level is rare.

As of Monday evening, authorities had not publicly identified the man who was killed.

Jordan, 30, whom hikers said called himself "Sovereign" on the trail, was charged with murder and assault with intent to commit murder. After an appearance in federal court in Abingdon, Virginia, on Monday, a magistrate judge ordered that he be held for a psychiatric evaluation.

Jordan's arrest affidavit details the weekend altercation, which took place in two counties within the George Washington and Jefferson national forests about 300 miles southwest of Washington. Four hikers reported that they first encountered Jordan on Friday evening in Smyth County, Virginia, and that he was "acting disturbed and unstable, and was playing his guitar and singing," according to the affidavit by FBI Special Agent Micah Childers.

The group continued north into Wythe County, Virginia, and set up camp there. Childers said the same man "spoke to the hikers through their tents and threatened to pour gasoline on their tents and burn them to death."

Fearful, the hikers decided to leave. But as they did, the man "approached them with a knife," Childers wrote. Two of the hikers escaped, called 911 at 2:30 a.m. and reported being chased by a man with a machete, the affidavit states.

The man then returned to the campsite, and one of the two remaining hikers argued with him, the affidavit states. The attacker then stabbed a male hiker in the upper body, while the female hiker ran, Childers wrote.

Wythe County Sheriff Keith Dunagan said the male victim sent an SOS signal on his phone, and the mobile service provider alerted deputies to his location just north of the Mount Rogers National Recreation Area.

Meanwhile, the attacker caught up to the female hiker, who had begun to tire. She turned to face the attacker "and raised her arms as if to surrender" when the man stabbed her multiple times, the affidavit states. The woman fell to the ground and played dead, and the man left, Childers wrote.

She then ran down the trail back toward Smyth County, where she met up with two other hikers. They helped her walk 6 miles into Smyth County, where they called 911 at 3:12 a.m., and the woman was taken to a hospital in Bristol, Tennessee.

Three hours later, tactical officers from the Wythe County Sheriff's Office were searching for the SOS signal when a dog, which authorities said belonged to Jordan, approached them. The animal led authorities back to Jordan, and he was taken into custody without incident.

Investigators then spotted the male victim and a 20-inch knife "in close proximity to the body" of the victim, the affidavit states. It says the surviving stabbing victim and the two hikers who escaped all identified the man who approached and attacked them as Jordan.

Nancy Dickenson, the federal public defender who represented Jordan at his first appearance, declined to comment on the case. Jordan's family members could not be reached for comment Monday.

Authorities said Jordan is from West Yarmouth, Massachusetts, but little could be learned about his life. In recent months, hikers had reported several run-ins with him.

Local police never found Jordan after the April 1 confrontation with Smith.

But hikers reported on online forums that the man known as "Sovereign" reappeared April 19 at a shelter near Hot Springs, North Carolina, where some hikers had settled in for the night. They said he threatened them by shoving his knife into one of the sleeping bags and burned a log book visitors use to document their trips. Then, he defecated all over the site.

Unicoi County, Tennessee, Sheriff Mike Hensley said he received reports on April 21 that Jordan was brandishing a knife and asking hikers for a password to get through a narrow opening to enter the trail in an area that sits along the Tennessee-North Carolina border called the Devil's Fork Gap. Hensley said Jordan showed up at a hostel on the Tennessee side that same day and said that "it was going to be a bad day for hikers on the trail."

Deputies arrested Jordan on April 22, charging him with marijuana possession and providing false identification after hikers refused to press assault charges. He was placed on probation and was released.

Since then, the community of hikers has been tracking Jordan's movements, using a GPS mobile app and social media to report dozens of incidents and appearances over two months while sharing intelligence to warn one another when he was close.

The accounts became familiar with hikers reporting that Jordan left trash and cotton socks - something skilled hikers don't wear - and was an aberration for the "trail family." In their telling, he violated unwritten rules of courteousness and good-naturedness that are part of the thru-hiking experience on the trail.

Ben Bolek encountered Jordan at a campsite a few days after Jordan was released from jail. Several hikers had claimed their sleeping spots at the shelter, so there was no space for Jordan. He set up a tarp nearby, cordoning off his sleeping area with medical tape, and began screaming and talking to himself, Bolek said.

Bolek said the hikers started a campfire but when Jordan came over, people dispersed.

"People were trying to avoid him at all costs," Bolek said. "Everybody around the trail knew who he was and what to expect from him."

Odie Norman, a self-described trail angel who helps take care of hikers, said he ran into Jordan on May 2 in Tennessee. He was determined to get him off the trail and convinced the man to board the 2:20 p.m. bus to Maryland. Jordan got on the bus, but he was seen in southwestern Virginia days before the fatal attack.

Hikers said that those who travel the trail are looking for peace and that it is not the "culture of the trail" to be confrontational or carry a gun.

"It's an accepting community of people trying to find themselves," said Bolek, of Austin, who recently quit his job at a large medical technology company.

After the attack, some hikers thought about going home, they said. The network of volunteers, hostel owners and hikers gathered at sites this weekend to check in with one another and help one another feel safe again, hikers said.

"We all rely on one another to keep the trail safe," Norman said. "We want to the world to know that we were violated by a flaw in the system and our hearts are broken."

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This article was written by Tom Jackman, a reporter for The Washington Post.